Alkali-soluble resins with non-colloidal silica for precoating diazotype materials



United States Patent ALKALI-OLUTLE RESKNS WITH NON-COLLOI- DAL SELECA FOR PRECOATENG DIAZOTYPE MATERIALS Douglas Straw, Binghamton, N.Y., assignor to General Aniline & Fiirn Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 20, 1962, der. No. 239,093

5 Claims. (Cl. 9675) The present invention relates to light sensitive diazotype materials and their preparation in which a base is precoated with a combination of a resin and a non-colloidal silica, followed by sensitization of the base and more particularly such material wherein the resin employed is a waterand acid-insoluble, alkali-soluble synthetic interpolymer containing anhydride or carboxy linkages.

to the sensitizing solution and the base coated therewith.

In another system, described in US. Patent 2,662,013, the base is precoated with non-colloidal silica and a watersoluble nitrogenous polymer such as casein, gelatin, glue and the like, after which the precoat is sensitized.

Still another system is described in U.S. Patent 2,822; 272 in which a vinyl polymer is added together with finely divided silica to the diazotype sensitizing solution. This procedure involves only a single step, but the maximum densities of the dyes formed after development are not fully satisfactory.

' These systems, however, are incapable of producing the clean, bright, crock-free, washfast diazotype prints demanded by the industry. In general, the main advantage is an improvement in the apparent dye density. No improvement in development characteristic ensues and, in

fact, in the case of the system of US. Patent 2,662,013, a

dullness ofthe print may result. On the other hand, it has been found that the system of US. Patent 2,566,709 often leads to excessive crocking and, in addition, does riot guarantee an improvement in wash fastness.

It has nowbeen discovered thatthe objections to the .prior art systems can be avoided with the realization of clear, bright, crock-free, wash-fast prints by precoating a base with a dispersion of a non-colloidal silica in an alkaline or ammoniacal solution of a normally water-insoluble interpolymer containing carboxy or anhydric linkages as the silica binder, drying this coating, and subsequently sensitizing the precoated base.

Diazotype materials and the process of preparing them in this fashion constitute the purposes and objects of the present invention.

The interpolymers, the use of which is contemplated hereirnfare described in Calvin E. Schildknec ts book Vinyl and Related Polymers, published by John Wiley and Sons, *Inc., New York, N.Y., and particularly in US.

' Patent 2,047,398, granted July 14, 1936, and are obtained by copolymerizing a monomer containing a single C=CH groupwith an ethylene-o -B-dicarboxylic acid or its anhydride. Examples of such copolymers are vinyl acetate-maleic anhydride copolymer and vinyl acetatemaleic acid copolymer. 1

ice

The copolymers used as a binder for the non-colloidal silica are not soluble in Water or acid but hydrolized gradually in water and may also be dissolved in dilute aqueous solutions of organic and/or inorganic bases such as ammonia, caustic soda, diethanol amine and the like to form the salts of the water soluble hydrolysis products of the copolymers. The solubility of the copolymers in these bases may be further promoted by the addition of low boiling aliphatic alcohols liquid at room temperature, such as methyl alcohol, ethyl alcohol, isopropyl alcohol and the like.

The silica employed for the precoat is a finely divided non-colloidal silica having an ultimate particle size ranging from about .1 to 10 microns (in terms of principal transverse dimension of the particle) and having an average particle size (based on quantity by weight of the particle) of not substantially less than 1 nor more than 5 microns, and preferably from 2 to 4 microns. The major portion by weight of the silica particle is preferably between 1 and 5 microns.

The ratio of silica to binder (copolymer) by weight amount of the dry non-colloidal silica. The precoate'd' base is then dried and sensitized with any of the conventional sensitizing formulations.

Such sensitizing formulations may make use of such light sensitive diazoniurn compounds as are disclosed in US. Patent 2,5 01,87 4 and in the article by Van der Grinten in the Photographic Journal, vol. 9213, 1952, page 46. StalbiliZfid diazos derived from N-substituted-p-phenylenediamines are most satisfactory and, in this connection, reference may be made to those diazos from N,N-diethyl-pphenylened-iamine; N-benzyl-N-ethyl-p-phenylenediamine, N-ethylp-phenylenediamine; Nfi hydroxyethyl-Nfmethylp-phenylenediamine and the like. According to the usual practice, these diazos are used in the form of salts stabilized with zinc chloride, cadmium chloride and the like.

Any of the usual coupling components are also satisfactory for my purpose. Examples of such couplers are 2,3 dihydroxy naphthalene; 1,8-dihydroxy-naphthalene; resorcinol; octyl resorcinol; p-methyl-N-phenylpyrazolone; 2,3-dihydroxy-naphthalene-6-sulfonic acid; 5,5-dimethyl- 1,3-cyclohexanedione; meta-hydroxyphenyl urea and the like.

The coating solution may also contain the various adjuncts usual in the manufacture of light sensitive diazotype materials. These includemetal salts for intensification of "the dyestuif image, such as ammonium sulfate, nickel sulfate, zinc chloride and the like; stabilizing agents such as thiourea, thiosinamine, naphthalene trisulfonic acid and the like; acids acting'to retard precoupling such .as

acetic acid, 'boric acid, tartaric acidand the like; hy-

groscopic agents such'as glycol, glycerin and the like; and

wetting agents such as saponin, lauryl sulfonate,'keryl .is converted into its less soluble form by the action of the acidic components of the sensitizing solution which has (J generally a pH between 1 and 2. This insolubilizing action is responsible in itself for a number of advantages attributable to the involved procedure, to wit:

(1) The components are trapped and mechanically held by the precipitation.

(2) The precipitation prevents penetration of the sensitizing components and concentrates them in a thin layer on the surface of the base. 7

(3) The physically trapped components are prohibited from migration and remain washfast.

Greatly improved development characteristics are also obtained with the prints made with my precoat. It is believed that such properties arise from the great aflinity of the precoat due to its acidic nature for alkaline vapors such as ammonia.

One of the outstanding features of my procedure is the discovery that the precoat adheres extremely well to a variety of bases heretofore sensitized only with the greatest difliculty. It has been my finding that it is now not only possible to sensitize such bases such as polyesterfilled glass cloth, polyester-filled cotton cloth, polystyrene film, polyvinyl acetate fim and the like, but also to obtain products with such materials having such outstanding characteristics as high dye density, excellent contrast, good washfastness of the resulting dyes, excellent pencil tooth and excellent development.

To summarize the advantages which are realized in following my principles are the following:

(1) Prints of improved dye density;

(2) Prints with improved brilliance;

(3) Prints free from crocking;

(4) Prints with white background, resulting in improved contrast;

(5) Prints having a desirable matte appearance free from feathering to ink line and possessing excellent pencil tooth;

(6) Prints having a generally improved surface and appearance over the same base material sensitized with the same formulation but without the subject pretreatment;

(7) Prints having improved development characteristics;

(8) Prints on otherwise diflicultly sensitizable bases.

The invention is illustrated by the following examples in which the parts are by weight unless otherwise stated. It is to be understood that the invention is not restricted to the examples.

Example I To 95 parts of water were added 7 parts by volume of 28 B. aqueous ammonia. To this solution were added v8 parts of the copolymer of vinyl acetate-maleic anhydride prepared according to the procedure described on page 367 of Schildknechts book Vinyl and Related Polymers. Under these conditions, an aqueous solution 'of the ammonium salt of the water-soluble vinyl acetatemaleic interpolymer was formed. Eight parts by weight of a finely divided, non-colloidal silica, as previously described, where then added and the slurry agitated until a uniform dispersion was obtained. This precoat solution Water to make 1000 mls.

The resulting material produces positive diazotype improved wash-fastness of the dye, superior pencil tooth, and superior visual dye density compared to prints of comparable diazo load on the same paper without the subject precoat or paper obtained according to U.S. Patent 2,662,013, US. Patent 2,566,709 or British Patent 717,- 835.

Example II The precoated paper as prepared in Example I is sensitized with the following solution:

Water mls 600 Ethylene glycol mls 50 Citric acid gms 50 Thiourea gms 50 Zinc chloride gms 50 5,5-dimethyl-1,3-cyc1ohexanedi0ne gms 10 p-Diethylaminobenzenediazonium chloride gms 10 Saponin gms 1 Water to make 1000 mls.

In this case, the prints obtained have a brilliant red positive image on a white backgorund, and show superior wash-fastness, pencil tooth, and development characteristics compared to prints made from paper coated with the same solution but Without the subject precoat or on paper obtained according to US. Patent 2,662,013, US. Patent 2,566,709 or British Patent 717,835.

Example III The precoated paper prepared in Example I is sensitized with the following system:

Water mls 600 Ethylene glycol mls 50 Citric acid gms 50 Zinc chloride gms 20 2,3-dihydroxynaphthalene-6-sulfonic acid gms 20 Resorcinol gms 4.5 Acetoacetanilide gms 1.5 p-Dimethylaminobenzenediazonium chloride gms 5 p-Diethylaminobenzenediazonium chloride gms 5 Saponin gms 1 The prints have a dark, neutral, black positive image on a white background and show superior wash fastness, pencil tooth, and development characteristics compared to prints obtained on the same paper with the same sensi tizing solution but without the subject precoat or on precoated papers cited in Example I.

Example IV To a solution of 2.5 parts, 28 B. ammonia, 15 parts methyl alcohol and parts water were added 15 parts of the copolymer of Example I. When solution was complete, 3 parts of non-colloidal, dry silica were added. When the pigment had fully dispersed, this solution was precoated onto polyester-filledglass cloth and dried.

This precoated base was then sensitized with the following solution:

Water mls 500 Isopropanol mls 250 Butanol mls Gamma-butyrolacetone mls 50 1 Formic acid mls 25 Citric .acid gms 25 Thiourea gms 25 Zinc chloride gms 25 Resorcinol gms 50 N,N-bis 2-hydroxyethyl) -p-aminobenzenediazonium chloride zinc chloride double salt gms 50 Prints made withthis material are sepia in color and appropriate as intermediates for making subsequent diazotype prints. In addition to having good dye density, pencil tooth, and development characteristics, the precoat enables the sensitization of this dimensionally stable base hitherto a difficult task. v

Example V The precoated glass cloth as prepared in Example IV is sensitized with the following solution:

Prints made in this case are yellow in color and appropriate for making subsequent diazotype prints. In addition, the prints have excellent pencil tooth, dye density and development characteristics.

Example VI The same precoating composition employed in Example IV was coated onto a polystyrene film. This pretreated base was then sensitized with the diazotype solution used in Example V. Prints made with this material are yellow in color and suitable as intermediates for making subsequent diazotype prints. In addition to having excellent dye density, pencil tooth, contrast, anddevelopment characteristics, this precoat enables the sensitization of a polystyrene basehitherto a difficult task.

Example VII A plastic coated paper was precoated with the following system:

'Parts Water 70 28 B. ammonia 0.2 Methanol 1.5 Copolymer of Example I 1.5 Non-colloidal dry silica 0.6

This precoated material was then sensitized with the diazotype solution employed in Example IV. Prints made with this material are sepia in color and have excellent pencil tooth, contrast washfastness, dye density, and development characteristics.

Example VIII A non-plasticized, calendered, Vinylite film base was precoated with the same composition as employed in Example IV. Such a pretreated base is then capable of sensitization with any of several diazotype formulations such as those employed in Examples I, III, IV, and the like. Prints made from such materials have excellent dye density, contrast, pencil tooth, washfastness and development characteristics. Further, the precoat allows the sensitization of Vinylite filrnshitherto a diflicut task.

Example IX Laquered cloth was precoated with the same composition as employed in Example IV and was sensitized with the following solution:

Water 2 mls Prints made from this material are sepia in color and are appropriate as intermediates for making subsequent diazotype copies. In addition, the prints have excellent 6 dye density, washfastness, contrast, development characteristics, and pencil tooth.

Example X 20 /2 lb. raw paper base was coated with the following composition:

Parts Water Sodium hydroxide 1 Copolymer of vinyl acetate and maleic anhydride 5 Dry, non-colloidal silica 5 This precoated paper was then sensitized with the following solution:

Water mls 600 Ethylene glycol mls- 100 Citric acid gms 50 Thiourea gms 50 Zinc chloride grns 50 2,3-dihydroxynaphthalene-6-sulfonic acid gms 20 Para-diethylaminobenzenediazonium chloride zinc chloride double salt grns 20 Saponin gm 1 Water to make 1000 mls.

Prints made from this material were a bright blue in color, have superior dye density, contrast, washfastness, pencil tooth, and development characteristics compared to prints made from this same sensitizing solution coated (1) The same raw base;

(2) The same paper precoated with casein and silica as per U.S. Patent 2,662,013;

(3) The samepaper treated according to the teachings of U.S. Patent 2,566,709 wherein the silica with no binder resin is either precoated on the paper from an aqueous dispersion or placed directly as a dispersion in the sensitizing solution.

Example XI A preco-at solution was prepared by dissolving 5 parts of the copolymer of styrene and maleic anhydride (sold as SC-2 Resin by Monsanto) in a solution containing 5 parts of aqueous ammonia (28 B.) and 100 parts of water. Five parts of dry, non-colloidal silica were then dispersed in this solution and the resulting combination coated on 20 /2 lb. paper. After drying, this precoated paper Was then sensitized with the same solution used in Example X.

Prints made from this material have a bright blue color and have superior dye density, contrast, washfastness, pencil tooth, and development characteristics compared to prints made from the same sensitizing solution and coated on: a

(l) The same raw paper base;

(2) The same raw paper base precoated with casein and silica as per U.S. Patent 2,662,013;

(3) The same raw paper base treated according to the teachings of U.S. Patent 2,566,709 wherein the silica with no binder resin is either precoated on the paper from an aqueous dispersion or placed directly as a dispersion in the sensitizing solution.

This application is a continuation-in-part of my copending application Serial Number 622,027, filed Nov. 14, 1956. r

I claim: r

1. Light-sensitive diazotype materials for producing positive prints from positive patterns comprising a base bearing a uniform coating of finely divided silica having a particle size ranging from .1 to 10 microns dispersed in a water-soluble salt of a watersoluble hydrolysis product of the copolymer of vinyl acetate and maleic anhydride, the ratio by weight of silica to copolymer ranging from 0.1 to 3.0, said coating having imbibed to the surface thereof, a light-sensitive diazonium compound and a coupling component.

2. The product as defined in claim 1, wherein the base is of a material normally unresponsive to aqueous sensitizing solutions.

3. The product as defined in claim 1, wherein the base is selected from the class consisting of polyester filled glass, polyester filled cotton cloth, polystyrene film, and polyvinyl acetate film.

4. Light-sensitive diazotype material as defined in claim 1, wherein said salt is selected from the group consisting of ammonium and alkali metal salts.

5. Light-sensitive diazotype material as defined in claim 1 wherein the ratio by weight of silica to copolymer rangcs'from 0.2 to 1.0.

References Cited in the file of this patent UNITED STATES PATENTS 2,047,398 Voss et al. July 14, 1936 Sulich et al. Dec. 8,

2,662,013 1953 2,699,392 Herrick et al. Jan. 1, 1955 2,746,863 KoSalek et al. May 22, 1956 2,805,159 Unkauf Sept. 3, 1957 2,322,271 Krieger Feb. 4, 1958 2,822,272 Kosalek et a1 Feb. 4, 1958 FOREIGN PATENTS 402,737 Great Britain Mar. 4, 1932 707,959 Great Britain Apr. 28, 1954 OTHER REFERENCES Fischer: Colloidal Dispersions, John Wiley and Sons,

. 15 1950, Second Printing, 1953, page 2.

Seymour et al.: Industrial and Engineering Chemistry, vol. 41, No. 7, July 1949, pages 1509-1513.

Schildknecht: Vinyl and Related Polymers, John Wiley and Sons, 1952, pp. 367-368. 

1. LIGHT-SENSITIVE DIAZOTYPE MATERIALS FOR PRODUCING POSITIVE PRINTS FROM POSITIVE PATTERNS COMPRISING A BASE BEARING A UNIFORM COATING OF FINELY DIVIDED SILICA HAVING A PARTICLE SIZE RANGING FROM .1 TO 10 MICRONS DISPERSED IN A WATER-SOLUBLE SALT OF A WATER-SOLUBLE HYDROLYSIS PRODUCT OF THE COPOLYMER OF VINYL ACETATE AND MALEIC ANHY DRIDE, THE RATIO BY WEIGHT OF SILICA TO COPOLYMER RANGING FROM 0.1 TO 3.0 SAID COATING HAVING IMBIBED TO THE SURFACE THEREOF, A LIGHT-SENSITIVE DIAZONIUM COMPOUND AND A COUPLING COMPONENT. 